package utils

import (
	"math/rand/v2"
	"strings"

	"github.com/gosimple/slug"
)

// BinarySearch BinarySearch
func BinarySearch(s []string, t string, n int) (idx int) {
	idx = -1
	if n == 0 {
		return
	}
	start, end := 0, n-1
	for start <= end {
		mid := (start + end) >> 1
		if s[mid] < t {
			start = mid + 1
		} else if s[mid] > t {
			end = mid - 1
		} else {
			idx = mid
			break
		}
	}
	return
}

var YesOrNo = map[bool]string{
	true:  "是",
	false: "否",
}

func GetRandomLetters(n int) string {
	const letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
	b := make([]byte, n)
	for i := range b {
		b[i] = letters[rand.IntN(len(letters))]
	}
	return string(b)
}

func GetPrefix(s string, n int) string {
	runes := []rune(s)
	if len(runes) <= n {
		return s
	}
	return string(runes[:n])
}

func GetSlugInfo(text string) string {
	return SanitizeSlug(slug.Make(text))
}

// SanitizeSlug 去掉 slug 中的横杠等特殊符号，只保留字母和数字
func SanitizeSlug(s string) string {
	s = strings.TrimSpace(s)
	if s == "" {
		return ""
	}
	var b strings.Builder
	b.Grow(len(s))
	for _, r := range s {
		if r >= 'a' && r <= 'z' || r >= 'A' && r <= 'Z' || r >= '0' && r <= '9' {
			b.WriteRune(r)
		}
	}
	return b.String()
}

// IsSlugAllDigits 判断 slug 是否全为数字
func IsSlugAllDigits(s string) bool {
	s = strings.TrimSpace(s)
	if s == "" {
		return false
	}
	for _, r := range s {
		if r < '0' || r > '9' {
			return false
		}
	}
	return true
}

// MakeUniqueSlug 生成唯一 slug；exists 返回 true 表示已被占用。生成结果不能全是数字。
func MakeUniqueSlug(source string, exists func(string) bool) string {
	pinyin := GetSlugInfo(source)
	if pinyin == "" {
		pinyin = GetRandomLetters(5)
	} else if IsSlugAllDigits(pinyin) {
		pinyin = pinyin + GetRandomLetters(3)
	}
	finalSlug := pinyin
	for exists(finalSlug) {
		finalSlug = pinyin + GetRandomLetters(3)
	}
	return finalSlug
}